Wells are generally drilled into subsurface rocks to access fluids, such as hydrocarbons, stored in subterranean formations. The formations penetrated by a well can be evaluated for various purposes, including for identifying hydrocarbon reservoirs within the formations. Flow connectivity of a reservoir is one parameter that impacts the hydrocarbon production efficiency. Asphaltenes are generally the heaviest fraction and the most polar component in a petroleum mixture. They can be precipitated as solid particles under certain pressure and temperature conditions in some crude oils. As reservoir pressure decreases, the pressure (at a given test temperature) at which asphaltene precipitation begins is referred to as the asphaltene onset pressure (AOP).
Formation evaluation may involve drawing fluid from a formation into a downhole tool. In some instances, downhole fluid analysis (DFA) is used to test the fluid while it remains in the well. Such analysis can be used to provide information on certain fluid properties in real time without the delay associated with returning fluid samples to the surface. Information obtained through downhole fluid analysis can be used as inputs to various modeling and simulation techniques to estimate the properties or behavior of petroleum fluid in a reservoir. These techniques can employ an equation of state (EOS) model that represents the phase behavior of the petroleum fluid within the reservoir, which can be used to determine various other fluid or reservoir characteristics.